Add contents length validation to send_to_paste_service util

It now raises errors instead of returning None on failing

1 files changed, 24 insertions, 6 deletions

diff --git a/bot/utils/services.py b/bot/utils/services.py
index 439c8d500..c10f0cd46 100644
--- a/bot/utils/services.py
+++ b/bot/utils/services.py
@@ -1,5 +1,3 @@
-from typing import Optional
-
 from aiohttp import ClientConnectorError
 
 import bot
@@ -9,18 +7,36 @@ from bot.log import get_logger
 log = get_logger(__name__)
 
 FAILED_REQUEST_ATTEMPTS = 3
+MAX_PASTE_LENGTH = 100_000
+
+
+class PasteUploadError(Exception):
+    """Raised when an error is encountered uploading to the paste service."""
+
+
+class PasteTooLongError(Exception):
+    """Raised when content is too large to upload to the paste service."""
 
 
-async def send_to_paste_service(contents: str, *, extension: str = "") -> Optional[str]:
+async def send_to_paste_service(contents: str, *, extension: str = "", max_length: int = MAX_PASTE_LENGTH) -> str:
     """
     Upload `contents` to the paste service.
 
-    `extension` is added to the output URL
+    `extension` is added to the output URL. `max_length` can be used to limit the allowed contents length
+    to lower than the maximum allowed by the paste service.
 
-    When an error occurs, `None` is returned, otherwise the generated URL with the suffix.
+    Raises `PasteTooLongError` if contents is too long to upload, and `PasteUploadError` if uploading fails.
+
+    Returns the generated URL with the extension.
     """
     extension = extension and f".{extension}"
-    log.debug(f"Sending contents of size {len(contents.encode())} bytes to paste service.")
+
+    contents_size = len(contents.encode())
+    if contents_size > min(max_length, MAX_PASTE_LENGTH):
+        log.info("Contents too large to send to paste service. ")
+        raise PasteTooLongError(f"Contents of size {contents_size} greater than maximum size {MAX_PASTE_LENGTH}")
+
+    log.debug(f"Sending contents of size {contents_size} bytes to paste service.")
     paste_url = URLs.paste_service.format(key="documents")
     for attempt in range(1, FAILED_REQUEST_ATTEMPTS + 1):
         try:
@@ -59,3 +75,5 @@ async def send_to_paste_service(contents: str, *, extension: str = "") -> Option
             f"Got unexpected JSON response from paste service: {response_json}\n"
             f"trying again ({attempt}/{FAILED_REQUEST_ATTEMPTS})."
         )
+
+    raise PasteUploadError("Failed to upload contents to pastebin")